New Skywatcher EQ Dob?

[IanL]

A few photos just popped up today on SkyWatcher's FaceBook page (https://www.facebook.com/SkyWatcherTelescope) showing this, but not been able to find any more information.

Looking at the images it appears to be a medium-sized closed-tube newt (maybe 10 or 12 inches or thereabouts) on an unusual looking Dob base - a nice open lattice affair for the alt-motion, but instead of a rotating base for az-motion, the tube appears to be pivoted between the 'arms of the alt-assembly.  Sort of like a fork mount turned on it's side or something you'd see in a big observatory scope.  Looks like it has a big motor/drive assembly built in to the base.  The display board behind says "EQ Dob - Development In Progress".

Haven't been able to find any other information but thought I'd give a heads up or see if anyone else knows what it's all about.

[astronymonkey]

Im not sure how it would work as moving the scope in altitude on its side bearings would change the angle of the pivot relative to polaris. Maybe it has something else in its design to make it work. Im not keen as it looks bulky so hopefully its just a prototype they are messing with but id be interested to see what they come up with.

cheers

[ronin]

Where does it fit?

If imaging then put a newtonian on an equitorial mount.

If manual visual then the present standard dobsonian mount does it all.

If a visual goto then there is already a goto dobsonian.

Would seem that the intended market is likely already covered.

[Blazar]

Does remind me of the Sumerian Optics truss dobs...though as you state, there is the pivot point on the base. I might be interested once they show how it all hangs together....also the 18" truss in the Facebook background I think is a new skywatcher one...we will wait and see...

[astronymonkey]

To me it looks as if there is no pivot on the base, just the alt bearings so the base is only for up and down. The left right movement seems to be provided on the pivot between the ends of the alt bearing, on the back of the tube.

cheers 

[Blazar]

Sorry meant to say base of the tube....

To me it looks as if there is no pivot on the base, just the alt bearings so the base is only for up and down. The left right movement seems to be provided on the pivot between the ends of the alt bearing, on the back of the tube.

cheers 

Yes the base of the tube...sorry if it was not clear.

[niallk]

The blurb on the poster says targeted at large aperture deep sky photography, no meridian flip, low center of gravity, ... Interesting design - nice to see new ideas - must search for skywatcher patent applications to see if any more details on mechanics are out there.

[IanL]

I guess it must be a computer driven alt-az mount similar to other goto dobs, just a different arrangement of the two degrees of freedom.  What I don't get is how that works for AP - you're going to get field rotation so unless they also have a camera rotator linked in there somewhere it's going to limit you in terms of exposure length.

[Moonshane]

look at the bottom 'plate'. it is clearly lower at the back (south) than the front (north) and sits on a triangular platform - i.e. three feet.

seems to me like an adjustable wedge a bit like a SCT fork would have. without motors and gears this would be an issue as when you turn east or west you'd lose balance but with gears etc should be good. the main advantage I'd think would be using a goto with EQ co-ordinates. whether it would be good for imaging depends like most things on accuracy of manufacture and set-up.

seems like a nice scope.

[IanL]

look at the bottom 'plate'. it is clearly lower at the back (south) than the front (north) and sits on a triangular platform - i.e. three feet.

seems to me like an adjustable wedge a bit like a SCT fork would have. without motors and gears this would be an issue as when you turn east or west you'd lose balance but with gears etc should be good. the main advantage I'd think would be using a goto with EQ co-ordinates. whether it would be good for imaging depends like most things on accuracy of manufacture and set-up.

seems like a nice scope.

There's nowhere near enough adjustment there for it to function as an equatorial wedge unless you are in equatorial latitudes though?

[ollypenrice]

I find it hard to see what's going in the picures but could this be a take on the equatorial platform principle where you don't need to tilt to the equatorial angle?

Why do you suppose we don't see more horseshoe mounts? My first thought was that this might be along those lines but I don't think it is.

Olly

[Peter Drew]

Looks like a good solution to the driven Dobsonian longer photography problem. A standard 2 axis driven unit will result in image rotation, this new SW  3 axis version should eliminate this. The OTA pivoting in RA should account for the rise or fall of the object being photographed as it approaches or passes the South point. This axis as well as the azimth axis would be driven. Not sure about "meridian flip".    

[Ptarmigan]

Instead of putting the de-rotator round the eyepiece axis they are doing it round the primary axis, ie. de-rotating the main tube, instead ?

Words like hammer and nut in that case ?? !

[TiTanecd]

However it works, as a pure technical piece of kit, would this be beneficial to have. A 12" or 16" to take dim objects? Any views from the experts?

Wouldn't this work similar to a eq base for dobs? Short tracking routines for a couple of minutes (10 degrees)?, down to the larger aperture. 

[Moonshane]

I find it hard to see what's going in the picures but could this be a take on the equatorial platform principle where you don't need to tilt to the equatorial angle?

Why do you suppose we don't see more horseshoe mounts? My first thought was that this might be along those lines but I don't think it is.

Olly

sorry yes, that's what I was getting at really. like an eqp I was assuming you revolve around Polaris in a cone shape so the angle will be 90 degrees minus your latitude, i.e. in my case 37 degrees.

[spaceboy]

It will be interesting to see how they incorporate polar alignment into the EQ platform. Going off the pictures and how the scope clamps in I'm guessing they will be selling the EQP as a standalone for those who already have solid tube newts/ dobs as well as a package for newcomers to the hobby.

[slickfonzy]

If they're saying it's good for AP, then my guess would be a self-rotating OTA to avoid the field rotation, as someone else mentioned.  Presumably you wouldn't need any sort of EQ platform/wedge then, either, as you could track in normal ALT/AZ and just rotate the OTA as you go?

[ollypenrice]

If they're saying it's good for AP, then my guess would be a self-rotating OTA to avoid the field rotation, as someone else mentioned.  Presumably you wouldn't need any sort of EQ platform/wedge then, either, as you could track in normal ALT/AZ and just rotate the OTA as you go?

De-rotated alt-az is fine since the professionals do just that but amateur autoguiding software will need to catch up and support it. There will be three, rather than two, dimensions to guide. No?

I have the distinct feeling that Peter understands this new system better than I do!! Im still fumbling with the pictures...

Olly

[Ptarmigan]

Mel Bartels and other advanced amateurs did this back in the 1980s

http://www.bbastrodesigns.com/fieldrot.html

http://www.bbastrodesigns.com/StepperSystem.html

Most of what they were doing with alt-az-rot is now plug&play thanks to Celestron et al.

except for a cheap* user friendly de-rotator !

maybe, enter the (drum roll )  Skywatcher EQ Dob !!!!

* there have been de-rotators offered for amateur use, but not as cheap as the 2axis alt-az mechanisms we now have.

[Alien 13]

Looks very interesting i hope skywatcher can make it work inovation in mount design does not come around too often most  today often rely on a flawed design (equatorial mount) with the use of systems to correct errors rather than a design that minimises errors in the 1st place i can only think of the astrotrac that has made an attempt to do this.

As Jeremy Clarkson would say "how hard can it be" to make a mount that can do unguided subs of 15mins or more at least with short to moderate focal lengths.

Alan

[ollypenrice]

Looks very interesting i hope skywatcher can make it work inovation in mount design does not come around too often most  today often rely on a flawed design (equatorial mount) with the use of systems to correct errors rather than a design that minimises errors in the 1st place i can only think of the astrotrac that has made an attempt to do this.

As Jeremy Clarkson would say "how hard can it be" to make a mount that can do unguided subs of 15mins or more at least with short to moderate focal lengths.

Alan

Very hard, effectively impossible. (There are things beyond Clarksonian comprehension... The relationship between excessive speed and death, for example. Or the distinction between killing yourself and killing other people.) Note that the so-called 'unguided' mounts like the ASA and 10 Micron are not really unguided. They guide on their own encoders in RA and on their encoders plus a sky model in Dec (though there will be interaction between the two so this is probably a simplification.) The incident angle of starlight changes the aparent position of a star as it rises and sets so simply having perfect mechanical sidereal tracking, even if this could be done, would not suffice. You need a feedback loop and this can be via guiding or management by encoder and sky model but a plain old mechanical solution is not going to cut it.

Olly

[Alien 13]

Thanks Olly my head allways new this but i had not thought about the changes in incident angle before and the fact that even perfect sidereal tracking wouldnt be enough.

Alan

[Ptarmigan]

There are things beyond Clarksonian comprehension... The relationship between excessive speed and death, for example.

Yea, waduseknow !

The bend at the end of the Mulsanne Straight wasnt that bad when I drove at it with excessive speed in the '60s,

and I'm still here (shhhhh !) without killing anyone (booooo !)

Wot I cant get my head round at this time of night is that it is said that field rotation is not so bad low in the east and west  but worse at other alt and az.

So, does this mean that the rotation of once per day (23h56min&bit) is at a variable rate during that time ?

_I think not_ but am in danger of doing a Descartesian vanishing act !

[Ptarmigan]

Oh bother, I ran out of edit time ! Sorry for a follow-on.

Olly, as always, said an interesting thing

" is not going to cut it."

Depends on your salami slicer !

also correctly mentioned feedback, once provided by the eyeball at the eyepiece

(feedback on the object is quite different from on the encoder)

and we are in danger of covering old ground

It depends !

for the neophite or someone wanting a snapshot for the diary or for dear old Perceval at Flagstaff whose eyes (or brain?) began to play tricks cos of too many hours at the eyepiece, etc&etc

these things are wonderous toys.

for the aspiring and dedicated amateurs they may fall short

but stacking in various degrees can be used by all from short lo long exposure peeps.

and for professionals, well , , above my pay grade.

but it is a matter of degree !

of fidelity,

compare the average amateur now with the Palomar survey !

So yes, pure mechanics are an aid but are inadequate in some respects.

To badly misquote Churchill ( or someone) "Yes madam we have your measure, it is now just a matter of cost "

Now, about this field rotation thing , , ,

[Laurie61]

Yea, waduseknow !

The bend at the end of the Mulsanne Straight wasnt that bad when I drove at it with excessive speed in the '60s,

and I'm still here (shhhhh !) without killing anyone (booooo !)

Wot I cant get my head round at this time of night is that it is said that field rotation is not so bad low in the east and west  but worse at other alt and az.

So, does this mean that the rotation of once per day (23h56min&bit) is at a variable rate during that time ?

_I think not_ but am in danger of doing a Descartesian vanishing act !

There is a nice explanation here of how your Lat and the RA/DEC of an object affects field rotation. 

http://calgary.rasc.ca/field_rotation.htm